Electric motor.



S. E. KURTZ.

ELECTRIC MOTOR. APPLICATION man FEB. 26. 1914.

Patented June 5,1917.

3 SHEETS-SHEET I.

S. E. KURTZ.

ELECTRIC MOTOR.

APPLICATION FILED FEB-26.1914- Patented June 5, 1917.

3 SHEETS-SHEET 2.

S. ELKURTZ. ELECTRIC MOTOR. APPLICATION FILED FEB-26,1914- Patented June 5,1917.

3 SHEETS-SHEET 3- In van tor.

i STATES PATENT OFFICE.

Specification of Letters Patent.

7 Application fled February 28, 1914. Serial Io. 821,127.

To all whom it may concern:

Be it known that I, SAMUEL ELLswoR'rH Kun'rz, a citizen of the United States of America, and a resident of Sac City, county of Sac, and State of Iowa, have invented certain new and useful Improvements in Electric Motors, of which the following is a specification.

The main objects of this invention are to provide an improved form of variable speed electric. motor; to provide a motor of this character adapted to operate on alternating current, and more particularly on a single phase current; to provide for running such a. device substantially as an lnduction motor; and to provide switching means connected and adapted for changing the speed.

Illustrative embodiments of this inventlon comprising several modifications are shown more or less diagrammatically in the accompanying drawings, in which- Figure 1 is an end elevation of one form showing the relative position of certain parts or members;

Fig. 2 is an axial section on "the line AA of Fig. l. I

Fig. 3 is an irregular cross section on the line I5B of Fig. 4, showing a modification.

i Fig. 4 is an of Fig. 3.

Fig. 5 is a partial section on the line DD of Fig. 6, showin another modification.

axialsection on the line CC Fig. 6 is a partial longitudinal section on the center line EE of Fig. 5.

Fig. 7 is a circuit diagram illustrating another modification and showing means for changing the speed.

Fig. 8 is an axial section of a modified form in which the principal members are arranged substantially in transverse parallel planes respecting the axis.

Fig. 9 is an axial section'of a modified form showing means for varying the resistance in the stationary squirrel cage circuits.

Fig. 10 is a broken section along the line FF of Fig. 9. I

' Fig. 11 is a conventional diagram of a modification showing a combination of direct and alternating current features.

Fig. 12 shows conventionally a portion of the field and load rotor members, the former having a plurality of independent field windings arranged the induced field.

Fig. 13 shows conventionally a similar portion, but with field circuit connections for energizing the outwardly facing poles by currents generated by inwardly disposed windings. Fig. 14 is a fragmentary diagram illustrating a divided circuit single-phase field winding for splitting the phase to produce a rotary field. 4

Fig. 15 is a diagram of connections for a three-phase rotary field which may be used for carrying out this invention.

In theconstruction shown, like numerals indicate like parts in all of the drawings. My improved form of motor comprises mainly a plurality of relatively movable members 1, 2 and 3 disposed alongside of one another in inductive relation. These members may be of cylindrical form and arranged concentrically, and for the pur-' pose of illustration are so shown in some of the views, as in Figs. 1 and 2.

The medial cylinder or ring is rotatably pivoted on a stationary axis. One of the adjacent members is stationarily mounted and the opposite member is pivoted coaxially with the middle member, the inner member 2 in this instance being shown stationary and the outer member 3 rotatable. The rotary middle member 1 is designated as the floating rotor, the adjacent rotary member 3 the load rotor, and the stationary member 2 the stator.

The said stator and rotor members 1, 2 and 3 are mounted on a fixed shaft 4 secured to a support 5. To this end they are for varyingthe speed of Patented June 5, 1917.

member 1 provided with armed hubs or spiders 6, 7

and 8 respectively. The spider 8 for the load rotor also carries rigidly a coaxially disposed driven member which may be in a of laminations field. Current of suitable character, as for instance single phase alternating current, 1s supplied to these windings through slip rings 15 which may be carried by the corresponding hub 6.

Wherever in this application single-phase current is represented or referred to as producing a rotary field, it is to be understood that any suitable means may be used for 1mparting the rotary effect, as for instance phase splitting, which is illustrated mIfigs. 1' and 14, wherein the field circuit 15 vided, one branch containing the main field coils 18 of low inductance, and another branch containing a correspondin number of supplementary coils 18 of re high inductance and disposed between the main coils. Any suitable means may be provided for cutting ter the machine is started, as understood in I the art.

4 In order to illustrate the novel features as simply and clearly as possible without showing readily implied details, only the main field coils are shown in Figs. 2 to 13, it being understood that details like or equivalent to those of Fig. 14'are included in practice to impart rotation to the field. Incase three-phase current is used in any instance, the field may be connected to produce a rotary field as shown in Fig. 15.

The stator ring 2 is of squirrel cage construction and reacts inductively to drive the field rotor in a negative direction respecting the opposite positive rotation of the field.

The load rotor 3 is also of squirrel cage construction, and by inductive reaction with the moving intermediate field of the medial member 1.is caused to rotate in the same direction therewith at a. somewhat less speed.

The magnetic portion of all three members, 1, 2 and 3 may to advantage be formed disposed radially and clamped together as usual in dynamo electric machinery. The stator2 and load rotor 3 are each provided with heavy end conductor rings 16 connected respectively by a uniformly distributed series of conductor bars 17 embedded transversely in the said rings, adjacent to their surfaces facing the field rotor 1.

In the form shown in Figs. 1 and 2, the

' field rotor 1 is represented for convenience by a Gramme ring having windin and oles arranged alternately, the windings 18 ing connected to produce alternate north and south poles of equal number on both the inner and outer sides of the ring as at 19 and 20. In operation the field rotor speed is equal to the speed of the revolving field therein, less the slip which is characteristic and which varies in proportion to the load. The resultant absolute speed of the field upon which the load rotor 3 depends is equal to the said slip of atively. v

out the starting coils af-' the field rotor and the speed of the load rotor is somewhat less thanthe said slip, due to the additional slip of the load rotor.

In the form shown in Figs. 3 and 4, the stator 2 is relatively short and there is provided in alinement therewith on said shaft 4 a field member 22, in this instance represented by a permanent magnet of composite structure comprising laminated sections 24, of substantially V-shape, formed and arranged to produce an annular series of outwardly projecting alternate north and south poles 25. The several groups of laminations are fastened to a hub member 27 secured by a fastening 28 to the shaft 4 and'having a radial web 29 to which the said sections are fastened as by bolts 31. The field rotor 1 in this instance is provided with two sets of windings 34 and 35, the former of which corresponds to a certain extent with the field windings 18 of Fig. 2 and is likewise arranged opposite the stator member 2, and the latter winding 35 comprises two parts. One of these parts is disposed on the inner side of the field rotor 1 opposite the stationary poles 25, and serves to generate alternating current, and the other part which is connected in series therewith, is disposed on the outer side of the field rotor facing the load rotor 3, and is ada ted and arranged to produce a rotary 'fie d thereon irrespective of the field produced on the inner side thereof. This outer rotary field produced by 'poles 20 reacts u on the load rotor 3 for driving the same. lhe speed of the said outer rotary field is proportional to the number of poles on the fixed field member 22 and inversely proportional to the number of poles on the outer side of the field rotor 1. Hence at a given speed of the field rotor the speed of the load rotor is determined by the number of poles on the fixed field member and on the outer side of the field rotor. In this instance the fixed field member 22 and the adjacent inner por: tion of the rotor 1 may be for instance, eight polar, as represented by poles 25 and 19 respectively, while the rest of said rotor is sixteen polar. 'Hence, the speed of the rotary field on the outwardly facing poles 20 is approximately half that of'the field on the poles 19 opposite the stator 2. By appropriate connection of the outer and inner portions of the windin 35 the outer and mner rotary fields pro uced b poles 20 and 19 respectively may be cause to ro-' tate either in the same or opposite 'directions, whereby their combined speed effect on the load rotor 3 will be either accumulative or differential as preferred. In both cases the field rotor 1 is driven at substantially the same speed. If the rotation of the fields of poles 19 and 20 is in the same direction on rotor 1, the effect with respect to rotor 3 is accumulative and vice versa.

mam

the present instance the speed of the load rotor is approximately either one-half or once and one-half as great as the field rotor.

In the form shown in Figs. 5 and 6 the field members 1 and 22 are both eight polar. Otherwise the various members are formed and arranged substantially as in Figs. 3 and 4, except with respect to the windings on the field rotor 1. In this instance the features of the first two forms shown in Figs. 2 and 4 are substantially combined. The exciting current from the slip rings is used in the windings 18 for energizing both the inwardly and outwardly facing poles on the field rotor. The energizing of the outwardly facing poles furthermore is supplemented by windings 35 such as shown in Fig. 4, re-

' ceiving current from generator coils disposed opposite the stationary field-member 22. In this instance the rotary fields produced by the primary and secondary currents respectively on the outwardly facing poles are nearly synchronous and in the same direction, wherefore they supplement each other.

In the form shown in Fig. 7 the fixed field member 22 and adjacent part of rotor 1 are eight polar, while the rest of rotor 1 is sixteen polar. Otherwise the various members are all formed and arranged substantially as in Figs. 4 and 6 with the exception that the two sets of energizing windings 37 and 35 for the outward-ly'disposed' poles on the field rotor 1 are arranged for alternate and independent action. The circuit for each of these sets of outer field windings respectively is led through appropriate slip rings to a switch 38 adapted and arranged for control by the operator to close either one circuit or the'other, whereby the said outwardly disposed poles may be energized eitherby the primary current in coils 37 from the outside source or by the second.- ary current generated in that part of the circuit 35 which is opposite the fixed magnet poles 25. These two energizing currents may be of different frequencies of any preferred ratio, depending for instance on the number-of poles on the fixed field member 22, whereby correspondingly different speeds may be attained by throwing the switch either one way Orthe other. In the present instance the speed is reduced one-half by throwing switch 38 from left to right.

Fig. Sillustrates how the principal members of my improved form of motor may be compactly arranged substantially'in trans verse radial planes on a short length of axle,

adapting it for use for instance in auto mobile trucks and the like. In-this embodiment the medial field rotor 1 is formed and arranged to present two sets of poles 19 and 20 facing parallel with the fixed axle or shaft 4 and in opposite directions respec: tively. To this end the spider 6 is formed hollow atone end in which is placed a pair 'rel cage, but when the ring 46 is moved forrectly to the inner side 9f the member 9, in

this instance in the fornf of a traction wheel.

Figs; 9 and 10 illustrate means for varying the reactive effect of the inner squirrel cage 42 upon the medially disposed rotor 43, by which means the torque and to some extent the speed of the latter may be controlled. For this purpose one of the end rings 44 is made of small cross-section and is of relatively high resistance as compared with corresponding rings 16 shown in the other fi res. In order to vary the eifective conductivity of the ring 44, a plurality of movable rin two being shown, 46 and 47, are rovided ad acent thereto and movable longitudinally and independently i'nto wedging contact with said ring 44. Said movable rings are carried .on separate hubs-49 and 50. The supporting shaft, 52 is formed,

of concentric control rods 54 and 55 connected to the hubs 49 and 50 respectively. .Said rods are movable longitudinally by means of a pair of hand levers 57 and 58 respectively, whereby one or both of the resistance control rings may be connected in the squirrel cage circuit to reduce its resistance. The shaft 52 and stator hub 59 are slotted at 52 and 59' to accommodate the support arms for the rings 46 and 47.

In order to provide a large and well defined contact surface to receive the ring 46 a series of conductor segments 60 are arranged inside the ring 44, said blocks being separated from each other by insulation or preferably by air gaps 61. The ring 44 may be of any suitable resistance material, as for i stance German silver. The'ring 46 may a so be of like material. The ring 47 and blocks 60 are preferably made of copper, in order to provide high conductivity.

.When the supplementary rings 46 and 47 are withdrawn, the resistance of the ring 44 prevents a large flow of current in the squirward into contact with the segments 60 and the ring 44 the current is increased somewhat depending upon the resistance of said ring, and then when the ring 47 is moved into operative position the resistance becomes practically negligible. The lower the resistance the greater the current and the nearer the speed comes to synchronism.

Fig. 11 illustrates the combination of direct current motor and induction motor effects. In this being disposed inwardly for reaction 11 on the duce and co -medial member 67 may shunt field of the member 65. The fie d portion of the member 67 is outwardly disposed rises a series of field les 71 havmg wm ings 72 and is excite by alternating current taken from taps on the armature winding at points 73 and 7 4 spaced 180 electrical de ees apart. Direct current is sup lied to t e shunt motor windings 69 and 75 rom the mains 76 and 77, one of which leads through a starting rheostat 79, said mains being connected to the direct current brushes 81 and 82 respectively disposed 180 electricaldegrees apart, The speed of the I be varied by varying the strength of the shunt field, which is connected through a field regulator 84. As the member 67 rotates alternating current is supplied to the outward-poles 71 which current produces a rotary field relative to said poles in either direction depending upon connections, and which may be made sub ect to control, as will be understood without showing detailed connections. Fig. 12'illustrates a modification of Fig. 11, in which the number of efiective poles on the rotor 85 may be variedv by means of a plurality of exciting windings 86 and 87, as shown in this instance in the form of two drum windings disposed in outwardly facing slots 89, one of said windings 86 being arranged to roduce twice as many oles as the other. hese' windings may be con: trolled by an suitable switching means, not shown, as wi 1 be understood. .Fig. 13 illustrates another modification of Fig. 11 in which the exciting current for the outwardly facing poles on the rotor 91 is generated independently of the armature windings proper crating windings 93 are disposed on-the 1nner side of the rotor and current is igenerated by reaction with the stationary eld. These generating windings 93 are connected to field windings 94 disposed upon the outer side of the rotor. The alternating currents nerated in the inwardly facing coils prouce alternating polarity in the outwardly facin field, whereby a rotary field is prowhich in turn reacts upon the outer member 3 for driving the same.

several embodiments of this insquirrel ca Althoug 69. In this-instance -gen-' member having vention are herein shown, it is to be understood that no attem show or enumerate al embodiments thereof which may be used to advantage, and that numerous details of the constructions shown may be altered or omitted without departing from the irit of this invention, as defined by the 0 owing claims.

I claim 1. An induction motor comprisin three concentric cylindrical members, one 0 which is adapted and arranged to serve as a field member, and is rotatably mounted, another of which is relativel short and stationarily mounted within the first member adjacent to one end thereof, and in inductive relation thereto, and the other of which is disposed adjacent to the outer surface of said field member, in combination with a fixed or stationary field member adjacent to the second member and occupying the space within the opposite end of sa1d rotary field member and in inductive relation with respect thereto, said rotary field member bein excited adjacent tosaid short cylindrica member by current supplied from an external source, and also havin conductors disposed partly adjacent to said fixed field member and part1 adjacent to the outermost member for t e generation and delivery of exciting current to the outer portion of said rotary field member, an external source of alternatin current from which said first ment has been mad tione current is supplied, and a circuit conpoles on one side, another series of ma etlc poles on the opposite side, each series ing wound and arranged to produce a rotary field, exterior and interior sources of alter,- nating current, independent circuits for supplying current from the outside source to energize the poles of each series respectively a circuit for energizing one series of am poles by current rom the interior source, and a switch arranged to close either of the circuits for the said. one series of poles.

3. An induction motor comprising a hub two sets of spider arms, in

combination with a power tranon member carried by one set, and a rotor member carried b the other set.

Signed at ac City this 23rd. day of February, 1914.

LYNN E. WrsmrAN.

ioq 

